A packaged substrate may be mounted on a printed wiring board for the purpose of interfacing a source of very high-frequency signals, e.g., an optical fiber, with other circuits also mounted on the printed wiring board. The interface may include a converter that converts the optical signal to an electrical signal and an amplifier that amplifies the resulting signal. A coaxial cable is typically used to connect the output of the amplifier to the other printed wiring board circuits. The prior art has recognized that such a coaxial connection is usually expensive and bulky.
One prior art arrangement uses a set of three so-called gull-wing lead connections in place of a coaxial cable connection. Specifically, the three gull-wing leads extend as terminals from the mounted substrate to three pads printed on the printed wiring board, in which a center gull-wing lead is the signal lead. The pads provide capacitive matching to compensate for the inductance exhibited by the center gull-wing lead at very high frequencies, e.g., up to four GHz. Accordingly, the capacitive compensation, to some extent, neutralizes the degrading effect of the inductance that the center gull-wing lead exhibits in the presence of very high frequency signals.
We have recognized, however, that such prior art compensation suffers from a number of transmission problems. Specifically, it does not deal with, for example, so-called group delay.